Conventionally, in an image forming apparatus such as an MFP (multi-function peripheral), if image formation or image scanning is not executed or there is no operation input for a preset sleep shift time, or if an operation input to designate a shift to a power-saving mode with lower power consumption is received, the operation state of the MFP is switched to a sleep mode (power-saving mode) with lower power consumption.
In the conventional image forming apparatus, when the normal operation state is restored from the operation state of the sleep mode in order to execute certain processing, control is performed to shift to the sleep mode again if a user carries out a power-saving operation to shift to the sleep mode again or if there is already a lapse of a sleep shift time in the state where no processing or operation such as image formation or operation input is executed again after the restoration.
Also, in the conventional image forming apparatus, if a reserved job with designated execution timing is set, control is performed so that the reserved job is constantly searched for even during the sleep mode and the reserved job becomes executed in the designated timing.
Moreover, in the conventional image forming apparatus, if it is not necessary to notify the user that processing is being executed and a job is executed without involving the operation of an image forming unit for forming an image, for example, if only a fax is received during the sleep mode, only the device in a part of the control board is started to execute the processing without lighting a display panel.
In this manner, conventionally, control is performed to shift to the sleep mode if no processing is carried out for a predetermined time or in accordance with an operation input. If certain processing is to be carried out during the sleep mode, control is performed to minimize the range of devices and functions to be awoken from the sleep state. Thus, power consumption is restrained. However, in the case of such control, a system that controls the entire MFP even during the sleep mode needs to be awake in order to control various jobs. Therefore, power consumption is not much restrained.